On platforms where closefrom returns void (eg glibc>=2.34) the prototype for closefrom in its compat tests would cause compile errors. Remove this and have the tests pull in the compat headers in the same way as the main code. bz#3336.
equivalent of LLONG_MAX for the compat regression tests, which makes them run on AIX and HP-UX. Patch from David Leonard.
Add first attempt at regress tests for compat library. ok djm@